Hacking the DF64 exit chute - Page 10

Grinders are one of the keys to exceptional espresso. Discuss them here.
j_bravo14

#91: Post by j_bravo14 »

Did not want to have any sub-par experience with the grinder :). The parts seemed to be printed by spec the mating parts to be magnetized fit well, same goes for the bowl spout at the end. Probably should have made that an FDM print. Once I fit this on the DF64 then we can further recommend to the rest going the JLPCB route. SLA printing is definitely much smoother and accurate than FDM.

Once I get the DF64 + SSP MP, will play around the metal dosing funnels to see which ones plays well with the modded chute.

Meantime, I'm playing around with an ODE with Cast burrs - surprisingly low retention with the metal knocker and right mods (direct chute hopper, tilted base - repurposed from DF64 tilted base).

NickMayers

#92: Post by NickMayers »

I know this is a little off-topic but I am really curious, how does a tilted base help the ode?
The burrs are vertically mounted so already gravity assists the grounds to go out of the grounds chamber.

j_bravo14

#93: Post by j_bravo14 »

Good point! I did open the grinder after 3 days of no bellows with the tilted base, but found a lot of grounds retained on side of the burrs that is pointing to the bottom of the grinder.

Looks like bellows will be a necessary thing for the ODE grinder. Also see that the bellows for the ODE is a little ineffective as the gap between the modded single dose hopper and the grinder intake lip needs to be sealed with some type of O-ring.

I have added an o ring on my vario between the grinder intake lip and allowed all the air to be focused on the grind path rather than blowing the powder on the top of the grinder between the hopper and grinder gap. You can also feel it in the bellows getting more resistance with the o ring in place.

999mor

#94: Post by 999mor »

Tried printing the button pusher in sla printer but it's keeps failing, the 2 parts always stuck together, I'm not sure if it's because of the sla or the file, because it's in .step needed to convert it to stl, tried couple of times, tried short exposure, but they are joined together.
Is in doomed to fail on sla? Maybe file issue? Can you please upload in stl and I'll give it another shot?

GDM528 (original poster)

#95: Post by GDM528 (original poster) » replying to 999mor »

There's no "doomed" in 3D printing :)

However, the button pusher is a two-part assembly specifically designed for FDM printing, and preferably single-wall. The parts are designed with zero clearance, so printing them together will likely bond them to each other. The two parts should be split up and printed separately. Apologies for not being more clear about that.

SLA printing the button pusher should be fine, but a bit wasteful on the resin. If there's an option to hollow out the models I'd consider it.

I updated the GrabCAD posting to include the .stl files of the button pusher.
https://grabcad.com/library/df64-exit-c ... ownspout-1

999mor

#96: Post by 999mor »

Thank you for your help. Just checked both of the files added, and they both are the same 2 parts joined together and can't be ungrouped. :shock: would you be kind to fix it?

GDM528 (original poster)

#97: Post by GDM528 (original poster) » replying to 999mor »


Oooops! I just learned something new about my CAD software. Thanks for pointing it out! Files are corrected now.

999mor

#98: Post by 999mor »

Update on my current situation.
I have ssp red speed for espresso.
I have printed in 0.05 and covered in clear coated.
After less then half kg, the chute got completely blocked that couldn't be released without dismantling the hoal chute and burrs.
Thought it was because of the clear coat, so printed again and did not covered the new parts with nothing and again after leaa then half a kg again started to clogged. This time was able to clean it with stick in the chute and removing the top burr, but i think it's because the red apeed burrs are grinding faster and the new chute cant handle it with the smaller opening port.
Maybe if i could slow feed the beans to the grinder.
Any suggestions?

GDM528 (original poster)

#99: Post by GDM528 (original poster) » replying to 999mor »

Sorry to hear about the clogging issue, especially having to dismantle it. The curvature of the exit chute allows a stick/probe to reach all the way to the burrs, so it's pretty remarkable that the coffee grounds would pack so firmly that a sharp toothpick can't break down the clog. Do you recall where the center of the clog was: top, middle, or bottom of chute?

The only maintenance I've performed is to tap the bellows after the last bean is ground, and roughly once a week giving the bellows several firm pumps into an empty catch cup to give the chute a good purge. After many kilograms it looks like this:



Some grounds are starting to accumulate at the top of the chute, perhaps from several experiments I've been running with extremely fine grind settings. In my case the effective aperture is actually getting a bit smaller. I'm going to resist the urge to scrape loose that accumulation to see if it eventually goes away, or gets larger.

I only grind 18g of dark roast at a time. I use a fine mist sprayer to moisten the beans and when I dump them into the hopper I let them sit for at least a minute to charge-equalize with the grinder. My typical grind setting is about 20-25 ticks from burr-touch. I'm not using any sort of base tilt. I always tap the bellows at the end of the grind while the grinder is still running.

I still have the factory-stock Italmill burrs - not familiar with the SSP burrs. I can imagine if they are grinding much faster, there could be a pileup of grind right at the top (input) of the exit chute. The cross-sectional area of the exit chute is specifically designed to be constantly increasing - especially at the top, so once the grind gets into the chute they should see more and more freedom of movement as they move down the chute. After you've cleaned and cleared out your chute, it would be informative to look up the chute after every grind to see if there's some spot in your chute where the grind is sticking.

It so happens I am working on slowing down the feed rate of the beans, in response to the clogging issues reported here. Slowing the feed rate may also produce a higher quality grind by reducing the congestion at the input to the burrs. The thread for the flow restrictor is here: Bean flow restrictor for DF64
Note the current design I posted is just an initial proof of concept, and I'm working on an improved version.

The flow restrictor has allowed me to grind finer without immediately causing a clog. When I do trigger a clog, it's always at the burrs. After the clog there is grind in the exit chute, but only because there's no longer any airflow due to the clogged burrs. Once I clear the burrs everything downstream also clears. You said you have the SSP burrs "for espresso", so what grind setting (from burr-touch) are you using?

999mor

#100: Post by 999mor » replying to GDM528 »

Yes the first time was really tightly packed blockage. The second time was much less worse... I think the blockage started lower, at the connection between the expansion chamber and the downspout, maybe because there is a step between those parts , and than due to not having enough airflow may cause upper accumulation.

Note that i no longer using the tilt base. And bellowing every time after the grind is done.

My burrs is red speed high uniformity, grind setting about 15-20 from burr touching, usually medium roast beans up to 20g